Fire alarm



Jan. 3, 1956 E, BLQOM 2,729,187

FIRE ALARM Filed June 9, 1953 United States Patent FIRE ALARM Eli 1;.Bloom, Philadelphia, Pa. Application June 9, 1953, Serial No. 360,577

Claims. (Cl. 116106) The present invention relates to fire alarms of thetype which operate a whistle from a supply of compressed gas when afusible plug is melted and opens an orifice.

A purpose of the invention is to obtain more sustained loud operation offire alarm whistles.

A further purpose is to make fire alarm whistles more quickly responsiveto change in air temperature.

A further purpose is to increase the volume of sound from fire alarmwhistles.

A further purpose is to simplify the mounting of an alarm whistle on apressure container.

A further purpose is to draw air into the gas stream from an alarmwhistle so as to augment the gas stream and increase the duration ofoperation.

Further purposes appear in the specification and in the claims. r

In the drawings I have chosen one only of the numerous embodiments inwhich my invention may appear, selecting the form shown from thestandpoints of convenience in illustration, satisfactory operation andclear demonstration of the principles involved.

Figure 1 is a perspective of the whistle in accordance with theinvention.

Figure 2 is a rear elevation, partly in axial section and showing thecontainer for the gas in phantom.

Figure 3 is a section of Figure 2 on the line 33 omitting the container.

Figure 4 is a section of Figure 2 on the line 44 showing the containerin phantom.

Figure 5 is an exploded fragmentary perspective showing the legsseparated.

The present invention is concerned with inexpensive temperature alarmscommonly called fire alarms, but useful also to show that an excessivetemperature has been reached on equipment such as electric motors,processing devices and the like. In devices of this kind, a container ofcompressed gas, suitably carbon dioxide, nitrogen, air, halogenatedhydrocarbon or the like, is provided with an orifice closed by a fusibleplug, which releases when a predetermined temperature is reached. Thegas passing out through the orifice operates a whistle or other audiblesignal and thus warns of the abnormal condition.

In the prior art such devices have been of limited utility because thenoise was, in some cases, of very short duration and in other cases notsufiiciently loud, and in any instance did not have an adequatecombination of loudness and duration to awake sound sleepers, or to beobserved by personnel momentarily at remote positions or distracted byother noises.

The present invention is designed to produce a device which will giveadequate loudness and also long duration, especially because the audiblesignal is produced by augmenting discharge of compressed gas with astream of entrained air.

Some of the prior art devices have also been subject to the objectionthat the response to change in temperature of the air was slow, and anemergency would often be far advanced before the signal operated. Thedevice 2,729,187 Patented Jan. 3, 1956 possible.

, The lower leg is tubular and has an internal diameter in inches of0.122 times orifice size times the gas pressure in p. s. i. $0.030 inch.

The lower tubular leg ends at a distance of 0.075 to 2.25 inches fromthe orifice.

The upper tubular leg is positioned at the end of the lower tubular legremote from the orifice, there being an open side between the upper andlower tubular legs, and the open side having a width corresponding tothe internal diameter and a length between 0.125 and 0.5 inch. The uppertubular leg extends at an angle of to degrees with respect to the lowertubular leg and the upper tubular leg has a length between 0.25 and 2inches. The upper tubular leg has an internal diameter of 1.5 to 3 timesthe internal diameter of the lower tubular leg.

The upper end of the upper tubular leg is closed.

In order to obtain more etficient utilization of gas pressure, there isdesirably a sharp lip on the end of the upper tubular leg adjoining theopen side, and this sharp lip is preferably located in prolongation ofthe center of the lower tubular leg. The outside edge of the lipdeviates from the prolongation of the lower leg as it extends away fromthe lower leg at an angle of 15 to 45 degrees.

Also to obtain more efficient utilization of the gas pressure, the lowertubular legis provided with a conical inlet at an angle of 15 to 75degrees on each side.

The whistle is preferably mounted on a pair of diverging feet, one ofwhich is removably attached. The attachment of the removable foot ispreferably by riveting an integral rivet portion extending through therivet openmg. 7

Considering the drawings in detail, the whistle comprises a lower leg 20and an upper leg 21, both of which have internal tubular bores. Theangles between the upper and lower legs vary betweenlOS and 140 degrees.A rib 22 extends across at the back between the legs and supports them.Suitably integrally formed, as by diecasting or plastic molding from therib 22 is a hang-up ear 23 having a suitable opening adapted to beplaced over a nail or held by a wire or the like. The material may bealuminum alloy, zinc alloy, copper alloy, phenolic plastic, polystyreneplastic or the like.

The lower leg has a suitably integral foot 24 mounted at one side andextending beyond the beginning of the lower leg at 25, and opposed tothe foot 24 is an opposite counterpart removable foot 26, which is heldin place after assembly by passing an opening 27 in the side of the footover a suitably integral rivet 28 and riveting at 30. a

The feet have at their lower ends projections 31 which engage in arecess32 of an interior flange 33 on the upper end of a pressure cylinder 34which has a suitably central orifice 35 normally closed by a plug 36 offusible metal.

With this it will be seen that the legs straddle the fusible plug andair can enter from either sideinto a space which has a diameterconforming to the following formula: 0.122 times the orifice diameterininches times the gas pressure in p. s. i. i0.30.inch.

The orifice diameter is likely to be of the order of 0.020 to 0.035inch, although itmay be as small as 0.015 inch oras large as0-.04-5inch. In any case the above formula will give the desired size of thebore of the lower leg.

The lower leg ends at 40 toa distance from the outside ofthe orifice 35'of :75 to 2.25 inches.

The lower leg is desirably provided with a conical inlet 41 whichincreases the efficiency of utilization of gas pressure, the angle ofeach side ofthe cone being between and 75 degreeswith respect to theaxis of the lower leg.

Since the upper leg is at an angle of 105 to 140' degrees with respectto the lower leg, there is an open side 42 opposite to the intersectingcorner 43- between the legs, and this open side desirably has a widthequal to the width of the upper leg and a length of between 0.125 and0.5 inch.

It has been found to be very desirable from the standpoint of moreeffective utilization of the high pressure gas to have an upper leg 21whose tubular internal bore 44 is from one and a half to three times thediameter of the lower leg. The upper leg is closed at the end remotefrom the orifice by a plug 45 making a press fit and flanged over. Theupper leg has a length measured from the edge 46 at the open side to theinterior end 47 of the plug of 0.25 to 2 inches.

More efficient utilization of the high pressure gas is assured if thelower outer end ofthe upper leg has a sharp lip at 46. The outer face 48diverges away from the axis of the lower leg as the face progresses awayfrom the orifice at an angle which is preferably between 15 and 45degrees.

It will be noted that the sharp lower edge 46 of the outside of theupper leg is located in prolongation of the lower leg substantiallyintersecting the axis of the lower leg.

It is desirable that a warning be given even to a person who may nothave been present when the alarm was operated. Also a warning is neededfor those who are hard of hearing. For this purpose it is desirable toinclude in the gas content of the cylinder an odoriferous material whichis expelled during operation of the alarm and which will create adistinctive odor calling attention to the emergency condition. Thequantity of such material will desirably vary between 0.25 and 1.0percent by weight of the compressed gas. The odoriferous material neednot 'be a perfume, but may be a material of unpleastantly distinctiveodor. Suitable examples of odoriferous material are as follows:benzaldehyde, vanillin, methyl salicylate, pyridine, nitrobenzine,acetophenone, coumarin, ammonium 'valerate, ethyl mercaptan.

In operation, the fusible plug of the compressed gas cylinder will besubjected to the ambient temperature by contact with the air or by heatconduction through the cylinder or noise-making device, and when itreaches an alarm temperature the fusible plug will melt and the gas willbegin-to flow outward. As the gas extends into the lower leg of thewhistle it will draw in or entrain air which will flow through the lowerleg and into the upper leg, vibrating and producing the whistle sound bythe combined action of the expanded gas and the entrained air.

The larger cross section of the upper leg, combined with the lengthdimensioning and angle dimensioning as described will assure a prolongedand loud noise. Most efiicient utilization. of gas is favored by theconical inlet and by the sharp lip.

When the audible alarm is over the odor will still remain as a furtheralarm.

In installing the device on the container, the fixed leg is insertedunder the flange, and then the removable leg is-fitted on the rivetandlikewise inserted under the 0pposite part of the flange of the cylinder.Slight staking or riveting will hold the removable leg in place andsecure the whistle on the cylinder.

In view of my invention and disclosure variations and modifications tomeet individual whim or particular need will doubtless become evidenttoothers skilled in the art, to obtain all or part of the benefits of myinvention without copying the structure shown, and I, therefore, claimall such insofar as they fall within the reasonable spirit and scope ofmy claims.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. In a fire alarm, a compressed gas cylinder having an orifice and afusible plug in the orifice and exposed to the air at the outside, incombination with a whistle mounted on the cylinder, comprising a lowertubular leg in prolongation of the orifice, the lower tubular legstarting at a distance of from 0.235 to 0.485 inch from the orifice,there being an air entrainment inlet at the side between the fusibleplug and the lower leg, the lower tubular leg having an internaldiameter in inches of 0.122 orifice size in inches times gas pressure inp. s. i. i0.030 inch, the lower tubular leg ending at a distance of 0.75to 2.25 inches from the orifice, feet connecting the lower tubular legwith the cylinder on either side of the air entrainment inlet, an uppertubular leg positioned at the end of the lower tubular leg remote fromthe orifice, there being an open side between the upper and lowertubular legs having a length between 0.125 and 0.5 inch, the uppertubular leg extending at an angle of 105 to 140 degrees with respect tothe lower tubular leg, the upper tubular leg having a length between0.25 and 2 inches, and the upper tubular leg having an internal diameterof 1.5 to 3 times that of the lower tubular leg, and a closure at theend of the upper tubular leg remote from the orifice.

2. A fire alarm according to claim 1, in combination with a sharp lip onthe end of theupper tubular leg adjoining the open side in prolongationof the center of the lower tubular leg, the outside edge of the lipdiverting from the prolongation of the lower leg as it extends away fromthe lower leg at an angle of 15 to degrees.

3. A fire alarm according to claim 1, in combination with a conicalinlet to the lower tubular leg at an angle of 15 to degrees at eachside.

4. A fire alarm according to claim 1 in which the feet are diverging,and one foot is removably attached to the lower leg;

5. A fire alarm comprising a first gas container having a closure at oneend provided with a vent opening, a fusible plug in the vent opening anda rim around the closure providing an inwardly directed annular recessat the edge of the rim, in combination with a whistle having a passagein line with the vent opening, having an ex tension at an end adjoiningthe container, having a first foot member on the whistle extensionprojecting outwardly into the recess, a rivet on the whistle extensionprojecting out oppositely to the first foot member and a second footmember having an opening to receive said rivet, to be secured thereby tothe said whistle extension and the second foot member projecting outfrom the whistle extension oppositely from the first foot member andengaged in the recess.

References Cited in the file of this patent UNITED STATES PATENTS243,158 Rector June 21, 1881 2,211,142 Loudon Aug. 13, 19.40 2,468,829La Porta May 3, 19.49

